1. Field of the Invention
This invention relates to an image forming apparatus for printing an image on a recording sheet that may be a sheet of plain paper.
2. Description of the Related Art
With image forming apparatus such as electronic copying machines, generally an electrostatic latent image is formed and then turned into a visible image, which visible image is subsequently printed onto a recording sheet of a predetermined size. Recording sheets of several given sizes are commercially available and a good printed image may be obtained if the visible image matches any of the given sizes of recording sheet. However, if the visible image does not match any of the given sizes of recording sheet, the size of recording sheet that is required for the printing has to be input to the image forming apparatus. With conventional image forming apparatus, the user is required to manually input the need of using one or more than one recording sheets that are out of any of the given sizes when the user wants to use such recording sheets. However, such a manual input operation is cumbersome particularly when recording sheets that are out of any of the given sizes have to be used frequently.
Additionally, the quality can differ significantly among recording sheets and there are various degrees of whiteness of recording sheets. In ordinary image forming apparatus, the printing density is selected on the basis of the average degree of whiteness of recording sheets. However, it is desirable to regulate the printing density so as to make it match the quality of the recording sheet to be used for printing. Additionally, while plane paper is normally used for recording sheets, it is necessary to change the printing density when an image is to be printed on a recording sheet that is different from plane paper such as an OHP sheet. Then, the quality of the recording sheet has to be manually input to the image forming apparatus to make the printing operation a cumbersome one.
Devices that comprise an information transmission means (RFID) for transmitting information on the size of the recording sheets contained in a sheet cassette in a non-contact manner is known (Japanese Patent Application Laid-Open Publication No. 2004-123366). However, no device that can acquire detailed attribute information on each recording sheet to be used for printing and automatically regulate the printing operation on the basis of the acquired information is known.